This article describes one journalist's attempt to find out something about Adam Gadahn who was named as a possible Al-Qa'ida terrorist in the US administration's latest warning about renewed threats of terrorism. (See also for instance the report and list here.)
If you do a google search for his name, you will find the account of his conversion to Islam reprinted on a large number of sites. You can also find his name and address (from his heavy metal days) here.
Of course it's possible that there's some genuine evidence of criminal activity against him. But as the Scotsman report says: The FBI wants to question the 25-year-old although it has no information connecting him to any specific terrorist activity.
The BBC's report today stresses the scepticism and cynicism with which this latest warning from the US government has been received.
It would be nice to think that this was simply a piece of electioneering and PR to divert public attention from Iraq, as has been done many times before.
Unfortunately, although that's the purpose, the government will be proved right in the end. There will be a major terrorist attack in the USA before the presidential election. And like the attacks of 11th September 2001, it will have the desired effect.
See: http://globalresearch.ca/articles/CHO405E.html for a new article about September 11th 2001.
See: http://www.wsws.org/articles/2004/jan2004/saf-j03.shtml for William Safire's prediction of a terrorist "October surprise". The original Safire article is apparently no longer freely available.
See also, for instance, this report of General Tommy Franks' prediction of the suspension of the constitution following a terrorist attack.